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Effects of Lysine on Growth of Tilapia Fed Diets Rich in Corn Gluten Meal

¹Biopolymer Research Unit, National Center for Agricultural Utilization Research, USDA, ARS, Peoria, IL 61604. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. ²Corresponding author. E-mail: wuyv@mail.ncaur.usda.gov Phone: 309/681-6364. Fax: 309/681-6689. ³Department of Agriculture, Illinois State University, Normal 61790. Current address: Department of Agronomy & Resource Sciences, Texas A&M University, Campus Box 156, Kingsville, TX 78363. ⁴Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47907.

Tilapia is a warmwater fish with mild flavor. Nearly 8.6 million kg are produced domestically, and ≈22.7 million kg are imported. Corn gluten meal (60% protein fraction) is a product obtained from wet-milling of corn. Diets (36% protein) containing 36–44% corn gluten meal with different levels of lysine and fish meal were formulated and fed to tilapia in aquaria for 12 weeks. Weight gain (WG) of tilapia fed diets containing the highest level of lysine (7.4% protein) with 4% fish meal was equal to that of fish fed a commercial control diet. Diets with lower lysine resulted in lower WG. The feed conversion ratio (FCR) and protein efficiency ratio (PER) of tilapia fed experimental diets containing adequate levels of essential amino acids and fish meal were the same as for fish fed the commercial control diet (also containing fish meal). Fish fed diets containing lower lysine levels had less favorable FCR and PER. This study shows that corn gluten meal is utilized at high levels in tilapia diets, particularly if essential amino acids are provided in adequate amounts.